With a recent increasing interest in eco-friendly resources, systems for generating hydrogen and oxygen using the sun light and water are being researched.
In a water splitting photoelectrode, the photoelectrode typically has a substrate/electrode/photoactive layer/catalyst structure, and when the photoelectrode operates, the cathode supplies electrons from the sun light to reduce water and thus generate hydrogen gas and the anode supplies holes to oxidize water and thus generate oxygen gas.
In this regard, Korean Patent No. 10-1724690 discloses a manufacturing method of water splitting photoelectrode based on Fe—Ni alloy by anodization and a water splitting electrode manufactured thereby.
Meanwhile, a transition metal is mainly used as a catalyst of a photoelectrode for cathode. In the case where the metal catalyst is used, the metal catalyst is desorbed or detached from the photoactive layer in a short time after redox starts, and, thus, the stability of the photoelectrode decreases over time.
Further, in the conventional photoelectrode for cathode, segregation of the metal catalyst occurs, and the metal catalyst desorbed from the photoactive layer is diffused into the photoelectrode or toward the electrolyte. Thus, photoelectrochemical properties of the photoelectrode may decrease over time.